False for CCENT : True for CCNA? Leased Line Bandwidth

dazerski

I received an INCORRECT on a practice question I was doing from the CD contained in the Odom/ICND1 book..I thought I was right because of a video I watched only last week.


Q: True or False" "A leased line between two routers provides a constant amount of bandwidth-never more, never less"

I said FALSE because in the CBTNugget video, Jeremy said there was a concept called "Bursting" that actually sometimes gave you more speed than you purchased but you were always guaranteed the minimum...

The answer key said I was wrong... "True: A leased line creates the cabling equivalent of having a cable between two routers, with the speed (clock rate) defined by the telco. Even when the routers have no data to send, the full bandwidth is available to be used"


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I dunno... it bothered me so I had to ask

sides14

I understand your logic for choosing your answer because you can purchase ethernet facilities that have bursting capabilities. Most leased lines are fixed rate (T1 1.544 mbps, DS3 45 mbps, Frac T1, etc.). It is always tough know what Cisco is actually looking for. I would be interested in seeing the exact question.

darkerosxx

I think what Jeremy is talking about in bursting is like Comcast that provides bursting capabilities to it's subscribers, but what they're talking about in the question is a line leased specifically for usage between two routers instead of part of a coax/fiber network like comcast, where you share the bandwidth with everyone.

When you purchase a line between two routers, you're the only one using the bandwidth, so you get what you pay for...nothing more, nothing less.

When you purchase service from Comcast, you get "up to X" speed, but it can and will be lower because you're sharing the connection with everyone else.

shednik

darkerosxx wrote:

I think what Jeremy is talking about in bursting is like Comcast that provides bursting capabilities to it's subscribers, but what they're talking about in the question is a line leased specifically for usage between two routers instead of part of a coax/fiber network like comcast, where you share the bandwidth with everyone.

When you purchase a line between two routers, you're the only one using the bandwidth, so you get what you pay for...nothing more, nothing less.

When you purchase service from Comcast, you get "up to X" speed, but it can and will be lower because you're sharing the connection with everyone else.

Best way to explain it right there, there is also a burstable T1 but I don't think they'll be asking you about one on the CCENT/CCNA

scheistermeister

If you want to know more about bursting look up Frame Relay. I don't know if it is covered in the new CCNA, but it was in the old.

dynamik

scheistermeister wrote:

If you want to know more about bursting look up Frame Relay. I don't know if it is covered in the new CCNA, but it was in the old.

They mention it briefly in the ICND 1 material. It looks like they get more in-depth in INCD 2.

dtlokee

It can depend on what type of link it is. A T1 is going to provide a fixed access rate of 1544 Kb/s, now if you are using frame relay over that T1 the provider may have the Virtual Circuits with a lower CIR + bursting capability up to the full access-rate, but they only guarantee to carry the CIR.